This invention relates to panel assemblies, and particularly to panel assemblies especially adapted for use as a window in vehicles, buildings or other structures, as well as a method for making such panel assemblies.
Relatively recent in the history of panel assemblies, gaskets have been molded or extruded directly onto the panel. In molded window panels, a sheet of glass is closed within a molding tool and a polymeric material is then injected on at least one surface of the panel and preferably proximate the peripheral edge. It is not uncommon for the polymeric material to be molded on three surfaces of the panel, encapsulating the entire peripheral edge. After the gasket is cured, the mold is opened and the panel assembly is removed.
To retain the molded window panel assembly within the vehicle, a bead of adhesive is often applied to the glass and/or gasket to bond the glass panel directly to the opening. Application of the adhesive bead to the gasket is desired so that the width of the pinchweld flange can be reduced. However, when the adhesive bead is applied to the gasket, window retention with the vehicle opening depends upon the adhesion of the bead to the gasket and also the adhesion of the gasket to the window panel. Any failure of these bonds can cause detachment of the panel assembly from the vehicle.
Studs, clips or other structures are often used in association with the molded gasket for a variety of purposes including acting as an attachment mechanism to the window opening, a temporary attachment until sealant cures, and as a positioning device or locater in the window opening. Traditionally, studs or clips are suspension molded within the polymeric material during the encapsulation process and act as the primary attachment mechanism to the window opening. The studs or clips, suspended within the hardened gasket, rely on the adhesion of the gasket material to the panel and the retention of the inserts (studs, clips) in the gasket to retain the panel in the opening. Thus, the window panel is retained within the opening by the bond between the gasket and the glass panel.
In another technique, studs or clips are bonded in an additional step directly to the glass panel inboard or outboard of the hardened gasket. In a typical configuration, the studs or clips are bonded directly to the glass panel at spaced intervals around the periphery of the gasket. One problem associated with this technique is that the attachment surface must be wider in order to accommodate both the gasket and the stud or clip. In some instances, the width of the frit layer commonly associated with such panels must be increased to conceal the studs or clips. The increase in width of the frit layer may partially obscure the field of vision through the panel. Moreover, the width of the pinchweld flange must be increased, or the width of the gasket reduced, in order to seal with the vehicle pinchweld flange and close the opening. Failure of any one of the individual, unsupported studs or clips reduces the integrity of the panel seal in the opening.
New vehicle styling requirements are calling for flush mounted glass panels having an exposed edge. To satisfy this requirement, the gasket material is bonded to at least a portion of one surface proximate the peripheral edge of the panel. Retention of the glass panel within the vehicle opening depends solely on either the adhesion between the gasket material and the glass panel or the retention of the suspended-stud or clip in the gasket. Failure of either one of these jeopardizes retention of the panel in the opening as the sealing integrity of flush mounted panel assemblies.